Here's why:
* Electronegativity: Oxygen has a much higher electronegativity than lithium. This means oxygen has a stronger pull on the shared electrons in the bond.
* Electron Transfer: The large electronegativity difference causes oxygen to essentially "steal" the electron from lithium. Lithium loses its valence electron, becoming a positively charged ion (Li+). Oxygen gains the electron, becoming a negatively charged ion (O2-).
* Electrostatic Attraction: The oppositely charged ions are then attracted to each other through electrostatic forces, forming a stable ionic compound.
Example: Lithium oxide (Li₂O) is formed when lithium and oxygen react. The formula reflects the charges of the ions: two lithium ions (Li+) are needed to balance the charge of one oxide ion (O2-).
Key points:
* Ionic bonds are generally strong and involve a complete transfer of electrons.
* The resulting compounds have high melting and boiling points due to the strong electrostatic forces between the ions.
* Ionic compounds are usually soluble in polar solvents like water.
